Purpose:

Gout is a common medical problem, with a world-wide prevalence of 12%. Most cases are managed and diagnosed by primary care physicians, and in a large number of patients without joint fluid analysis.We performed a study to estimate the validity of signs and symptoms for gout arthritis in primary care, and to develop a diagnostic rule for gout without the need of synovial fluid analysis.

Methods:

Patients with a mono-arthritis were recruited from an open population of 330,000 Dutch inhabitants. Patients with a gout diagnosis according to family physicians (FPs) were enrolled in a diagnostic study (March 2004 through July 2007). Clinical variables, including the presence of monosodium urate (MSU) crystals in the synovial fluid of the affected joint, were collected within 24 hours of presentation to the FP. Statistical significant variables selected after univariate regression, and variables predefined by external knowledge and availability in primary care, were entered in multivariate logistic regression models to predict the presence of MSU-crystals in the synovial fluid. The diagnostic performance of the models was tested. The most appropriate model was transformed to a clinically useful diagnostic rule.

Results:

There were 328 patients included. The most appropriate model contained the predefined variables 'male gender', 'acute (mono-)arthritis before', 'onset within one day', 'joint redness', 'MTP1 involved', 'hypertension, or one or more cardiovascular diseases', and 'serum uric acid>0.35mmol/l'. This model had a ROC-area of 0.85 (95%CI 0.810.90). The performance did not change after transforming the regression coefficients to easy-to-use scores and was nearly equal to the statistical optimal model (ROC-area 0.87; 95%CI 0.830.91).The final prediction rule after transforming the shrunken regression coefficients resulted in the following clinical scores:Male gender:2,One or more previous attacks:2,Onset within one day:0.5, joint redness:1, Joint location MTP-1:2.5,Hypertension, or one or more CV diseases;1.5,Serum uric acid>0,35mmol/l:3,5.The prevalence of gout at 3 cut-off points were:<=4 points,2%;>4 and <8 points,31% and >=8 points 80%.

Conclusion:

In this study a diagnostic rule for gout was developed, that can be used validly by primary care physicians without joint fluid analysis.In addition it can be used for research purposis